Mixers are in wide use in a number of industries, including for example medical, pharmaceutical, food, and biotechnology industries. Many of these mixers typically involve a shaft that extends into a vessel to drive a number of impellers which impart a mixing force to the material being mixed inside the vessel. Typically, the shaft is mounted to extend into the vessel by some form of mounting arrangement that also supports a drive motor.
In some types of mixing systems, a seal is located where the shaft enters the vessel to contain material being mixed inside the vessel and also to prevent contaminants outside the vessel from entering the material to be mixed. Some industries have particularly high sanitary requirements in this regard. In response, a type of mixer drive has been developed in which a magnetic drive is provided having an internal canister to positively and completely seal the vessel. The motor on the outside of the canister drives a magnet rotor outside the canister and the shaft inside the vessel has a magnet rotor inside the canister. In this type of arrangement, the motor drives the shaft to drive the magnet rotor that is located outside the canister, the canister remains stationary and the magnet rotor for the impeller shaft is driven by the rotating magnetic field induced by the outer magnetic rotor. Examples, of these types of magnetic drive systems can be found for example in U.S. Pat. No. 5,368,390, to Gambrill et. al, issued Nov. 29, 1994, which is hereby incorporated in its entirety by reference, and U.S. Pat. No. 5,427,450, to Gambrill, issued Jun. 27, 1995, which is also hereby incorporated in its entirety by reference.
The arrangement disclosed U.S. Pat. No. 5,427,450 provides many advantages, including the ability to flush and clean the components which are located inside of the canister in some situations without needing disassembly of the drive system. However, although the system described in U.S. Pat. No. 5,427,450 is very advantageous it is still desired to have improvements to this type of system, such as for example providing a simpler system using fewer parts, and the provision of a system which can if desired provide an even more sanitary arrangement in some applications after it has been cleaned.
Accordingly, there is a need in the art, for an even improved magnetic mixer drive system, which can be cleaned in place.